1 12 13 14 15 16 231 Replies Latest reply on Sep 25, 2012 5:22 AM by Roger Wolff Go to original post
      • 196. Re: RG1 1.8v regulator
        Roger Wolff

        Peg,

        Check out Aoyue. http://www.aoyue.com/en/ArticleShow.asp?ArticleID=372

        For a little over $125 you might be able to get a combination station that also does hot-air. I have the just-hot-air station from them. (and the weller)

        • 197. Re: RG1 1.8v regulator
          morgaine

          I don't know of one yet, but I'm definitely in the market for one because under 14X binocular magnification it's really hard to control an iron with a long tip.  Currently looking through jamodio's links.

           

          Addendum:

           

          • The iron that comes with Adafruit's Hakko FX888 Soldering Station seems to be 190mm long without cord, and the tip looks kinda long.
          • Newark's Tech Data Sheet link for the Weller WES51 is currently down for me, I'll check again later.  On Farnell UK, no such model, might be US-only.
          • Weller have a "micro" range WHS-M,  http://uk.farnell.com/weller/whs-m-uk-eu/soldering-staion-40w-230v/dp/1729967 , which looks very small, but I can't see the actual tip length specified.

           

          General comment about Weller pricing ... ouch.   It's clearly industrial pricing, hard to justify for very occasional use.

           

          Morgaine.

          • 198. Re: RG1 1.8v regulator
            Tooms

            Hi

             

            I am in the process on testing how little power the RPI can use and what heat there is, so i will just share some small limit results with you.

             

            In the test setup i have:

            Disconnect the LAN9512 from the main 1V8 power rail on the board.

            Add caps to te LAN9512 as the SMSC pdf says

            Removed the RG1

            Removed the RG2

             

            I have then connected external power supplys for the 1V8, 3V3 and 5V0 Rail and on each rail there is an volt and amp meter so i can see how many V and mA there is used on each rail.

             

            Here is when the RPI is just power up and is idle

            Rail 1V8          1,8000V * 0,06338A = 0,114084W

            Rail 3V3          3,3400V * 0,02460A = 0,082164W

            Rail 5V0          4,9900V * 0,04605A = 0,022979W

            Idle mode total = 0,426038W

             

            Here is when the RPI calc PI

            Rail 1V8          1,8000V * 0,06351A = 0,114318W

            Rail 3V3          3,3300V * 0,02710A = 0,090243W

            Rail 5V0          4,9200V * 0,07973A = 0,392272W

            RPI calc PI total = 0,596833W

             

            Note: the reason it is the 5V0 rail there is having higher mA when calc PI is because i have not removed the RG3 from the board, the RG3 is feed the CPU with 2V5 from the 5V0 rail.

             

             

            wow this is much lower then i was thinking it was using and it seems there is alot to save with an very good switch mode regulator..

             

             

            So this was just to share some test details with your guys.

             

             

            Tooms

            • 199. Re: RG1 1.8v regulator
              pegwag

              I found other discussions regarding this question. Sorry to have jumped in to the wrong discission. . . I'm going to check into the chinese market. Thanks for the suggestions. I'll let you know what I come across for soldering irons. The "re-work" stations have me confused. . .like what would I ever need a hot air gun for??

              Best,

              Peg

              • 200. Re: RG1 1.8v regulator
                John Beetem

                Tooms wrote:

                 

                wow this is much lower then i was thinking it was using and it seems there is a lot to save with a very good switch mode regulator..

                Thank you for sharing your measurements.  Those numbers do seem low, but calculating pi probably doesn't use much RAM.  I believe the power consumption goes up a lot with:

                 

                1.  Large computations that don't fit in cache, so there's lots of DRAM activity.  Large compiles are good candidates.

                 

                2.  Heavy GPU use such as 3-D graphics and video decode.  Those would also have a lot of DRAM traffic.  I don't know how much HDMI adds in when active.  I know my RasPi draws more current when X Windows comes up.

                 

                3.  Ethernet, which has 50 Ohm pull-up connected to +3.3V.  USB probably uses a lot when it's driving.

                 

                I remember my board being quite a bit warmer with Ethernet hooked up, so I typically just connect it for a few seconds to get the correct time and then leave it disconnected.

                • 201. Re: RG1 1.8v regulator
                  John Beetem

                  Peg Wagner wrote:

                   

                  The "re-work" stations have me confused. . .like what would I ever need a hot air gun for??

                  A soldering iron is great for soldering or desoldering a single terminal.  It doesn't work well if you want to heat up multiple terminals simultaneously, such as the two terminals of an SMT resistor.  And if you want to desolder the LAN9512 chip, forget it.  You have to heat up 64 tiny terminals plus a large ground pad under the chip which you can't even touch with the iron.

                   

                  The right hot air tool makes it possible to desolder these kinds the packages, and resolder all pins at the same time.  But you do need to know what you're doing (which I don't).

                  • 202. Re: RG1 1.8v regulator
                    Roger Wolff

                    Tooms,

                     

                    When you're not feeding the 'pi externally with those powersupplies, all these are derived with a linear regulator from the 5V. So while your measurement says

                     

                    Rail 1V8          1,8000V * 0,06351A = 0,114318W

                     

                    That would be 1.8V rail: 5V * 63mA = 315 mW if you hadn't modified your 'pi.

                     

                    So in fact, we can calculate the power-use of you'r pi by just adding all the currents:

                     

                    Itot = 63 mA + 27 mA + 79 mA = 169 mA total.

                     

                    My measurements said that the 'pi was using about 400mA (+/- 40mA depending on system load and Video). Others have done similar measurements and also measured values in that range. So your measurements differ by more than a factor of two from previous measurements.

                     

                    Can you double check?: It seems there  is a measurement error.

                     

                    Things to try: Restore the 'pi to the original state and measure 5V consumption. I expect on the order of 400mA. Not 170mA as you're seeing now.

                     

                    P.S. Those linear regulators are very "efficient"in that they don't "waste" any current. They are powered from the voltage difference between output and input. Almost all the current is fed into the load. An 1.8V regulator delivering 63mA, will draw very close to 63mA from its powersupply. Even an old one like the LM1117.

                    • 203. Re: RG1 1.8v regulator
                      Tooms

                      John Beetem wrote:

                       

                      Tooms wrote:

                       

                      wow this is much lower then i was thinking it was using and it seems there is a lot to save with a very good switch mode regulator..

                      Thank you for sharing your measurements.  Those numbers do seem low, but calculating pi probably doesn't use much RAM.  I believe the power consumption goes up a lot with:

                       

                      1.  Large computations that don't fit in cache, so there's lots of DRAM activity.  Large compiles are good candidates.

                       

                      2.  Heavy GPU use such as 3-D graphics and video decode.  Those would also have a lot of DRAM traffic.  I don't know how much HDMI adds in when active.  I know my RasPi draws more current when X Windows comes up.

                       

                      3.  Ethernet, which has 50 Ohm pull-up connected to +3.3V.  USB probably uses a lot when it's driving.

                       

                      I remember my board being quite a bit warmer with Ethernet hooked up, so I typically just connect it for a few seconds to get the correct time and then leave it disconnected.

                       

                      Hi

                       

                      yes this was just an small test, my plan is todo this things when load testing

                       

                      * copy files via network

                      * take images via webcam (my not do this because then the webcam load is part the setup)

                      * calc PI

                      * use omxplayer to play an mpeg4 movie

                       

                      so by this it will do more load on it when testing.

                      • 204. Re: RG1 1.8v regulator
                        Tooms

                        Roger Wolff wrote:

                         

                        Tooms,

                         

                        When you're not feeding the 'pi externally with those powersupplies, all these are derived with a linear regulator from the 5V. So while your measurement says

                         

                        Rail 1V8          1,8000V * 0,06351A = 0,114318W

                         

                        That would be 1.8V rail: 5V * 63mA = 315 mW if you hadn't modified your 'pi.

                         

                        So in fact, we can calculate the power-use of you'r pi by just adding all the currents:

                         

                        Itot = 63 mA + 27 mA + 79 mA = 169 mA total.

                         

                        My measurements said that the 'pi was using about 400mA (+/- 40mA depending on system load and Video). Others have done similar measurements and also measured values in that range. So your measurements differ by more than a factor of two from previous measurements.

                         

                        Can you double check?: It seems there  is a measurement error.

                         

                        Things to try: Restore the 'pi to the original state and measure 5V consumption. I expect on the order of 400mA. Not 170mA as you're seeing now.

                         

                        P.S. Those linear regulators are very "efficient"in that they don't "waste" any current. They are powered from the voltage difference between output and input. Almost all the current is fed into the load. An 1.8V regulator delivering 63mA, will draw very close to 63mA from its powersupply. Even an old one like the LM1117.

                         

                        yes it is looking very low but i have looked and recheck the setup and it all seem to be correct.

                         

                        My RPI is also using around 400 +/- mA so yes it is low the 170mA

                         

                         

                        But for more testing i have to make an plan of testes an follow, but this post was just to share with your guys that it seems to alot to gain bu replacing the regulators.

                         

                         

                        Thomas

                        • 205. Re: RG1 1.8v regulator
                          Roger Wolff

                          Well, IMHO, the first thing to do is to measure where that missing 230mA goes to....

                           

                          P.S.

                          Rail 5V0          4,9900V * 0,04605A = 0,022979W

                          is wrong. That's 0.23W.

                          • 206. Re: RG1 1.8v regulator
                            Tooms

                            Hi

                             

                            your correct, it is an calc error from my side

                             

                             

                            Here is an new calc of the idel mode

                             

                            Rail 5V0          5.01V * 0,04595A     =     0,2302095W

                            Rail 3V3          3,35V * 0,02830A     =     0,0948050W

                            Rail 1V8          1,83V * 0,06317A     =     0,1156011W

                            Total watt                                         =  0,4406156W

                             

                             

                            Tooms

                            • 207. Re: RG1 1.8v regulator
                              John Beetem

                              Roger Wolff wrote:

                               

                              P.S. Those linear regulators are very "efficient"in that they don't "waste" any current. They are powered from the voltage difference between output and input. Almost all the current is fed into the load. An 1.8V regulator delivering 63mA, will draw very close to 63mA from its powersupply. Even an old one like the LM1117.

                              However, linear regulators are inefficient in that they waste power by converting the voltage drop into heat.  A switching regulator uses less average input current to produce the same average output current.

                              • 208. Re: RG1 1.8v regulator
                                Tooms

                                Hi guys

                                 

                                As promised, I have now finished testing and it toke alot more work then i had expected but here is a blog post with all the details

                                 

                                http://www.tooms.dk/Tblog/Showblog1.asp?BlogID=201208292042561198

                                 

                                So now the hunt for a LDO replacement

                                 

                                 

                                Hope you like it.

                                 

                                Thomas

                                 

                                • 209. Re: RG1 1.8v regulator

                                  A report that severing 1.8v from the lan chip prevents crashing:

                                  http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=14489&start=55

                                   

                                   

                                  A report that adding heatsink and fan prevents problems booting:

                                  http://www.raspberrypi.org/phpBB3/viewtopic.php?f=26&t=14137&start=4